Nerve block is a therapeutic method for blocking pain signaling from a nerve(s) that is causing pain, which uses local anesthetic to be injected directly onto the nerve or into the neighboring tissue with needle or the like (Non Patent Literatures 1 and 2). For nerve block, injections are made in various areas including rectus sheath, transversalis fascia, and the like, and conventional approaches for nerve block include the landmark approach, electrical stimulation approach, and the like. In recent years, an approach in which nerve blocks are performed under ultrasonography is going mainstream.
Nerve blocks must be performed by specialist anesthesiologist because excellent technical skill is required to have injections made at target sites. However, even an anesthesiologist can make operational mistakes such as penetrating through a target site. For example, cases of complications such as peritoneal punctures accompanied with intraperitoneal organ punctures have occurred here and there in association with the growing significance for truncal blocks due to the increase in the number of patients receiving anticoagulant therapy.
Ultrasonography is often utilized in vascular puncture as well, for example, in emergency situations such as in emergency outpatient service. In such situations, patients can be in critical conditions due to bleeding or the like and thus, in general, even an operator who is highly skilled in vascular puncture, such as an anesthesiologist, would utilize ultrasonography to perform vascular puncture for safety's sake. In emergency cases, however, such operator with excellent technical skill may not be always available; consequently, even when ultrasonography is utilized in order to confirm the target blood vessel, operational mistakes can still occur.